Gearbox



Jan. 16, 1951 BLUMENBAUM 2,538,665

GEAR BOX Filed July 8, 1948 4 Sheets-Sheet l INVENTOR. Z oazs B/zz/we/7%a(m ATTORN EYS- Jan. 16, 1951 BLUMENBAUM GEAR BOX 4 Sheets-Sheet 2 Filed July 8, 1948 ATTORNEYS.

Jan. 16, 1951 BLUMENBAUM GEAR BOX 4 Sheets-Sheet 4 Filed July 8, 1948 Patented Jan. 16, 1951 GEARBOX Louis Blumenbaum, Cranston, R. I., assignor to Scott Testers, Inc., a corporation of Rhod Island Application July 8, 1948, Serial No. 37,677

12 Claims.

its design to one particular type of testing. If

the specimen is to be subjected to a tensile test,

a gear unit is employed which operates to provide a particular motion adapted to conduct the test. When the specimen is subjected to a test for hysteresis, a difierent unit is employed operable to provide a different motion. It is desirable to provide in a testing machine a single unit or gearing mechanism operable to provide a motion adapted to conduct a tensile test and a motion to conduct a hysteresis test An object of the invention is the provision of a gearing mechanism for a testing machine so constructed as to combine the motion cycles heretofore transmitted from two separate gearing units. V

Another object of the invention is the provision of a gearing mechanism for a testing machine so constructed as to combine the motion cycles heretofore transmitted from two separate gearing units and to be controllable by the operator to select either of these motions or to change from one to the other at will during the progress of a test.

Another object of the invention is the provision in a testing machine equipped with a reciprocating rack for applying a work stroke to the specimen of a gearing mechanism for reciprocating the rack wherein the change of direction of movement of the rack will be repetitive at definite points.

Another object of the invention is the provision in a testing machine equipped with a reciprocating rack for applying a Work stroke to the specimen of a gearing mechanism for reciprocating the rack at a uniform speed in either direction.

Another object of the invention is the provision in a testing machine equipped with a reciprocating rack for applying a work stroke to a specimen of a gearing mechanism for moving the rack at a uniform speed on the work stroke thereof and at an accelerated speed on the return stroke.

Another object of the invention is the pro-.

Another object of the invention is the provision in a testing machine equipped with a reciprocating rack for applying a work stroke to the specimen of a gearing mechanism for reciprocating the rack wherein the change of direction of movement of the rack may be manually controlled in either direction during the travel thereof.

With these and other objects in view, the invention consists of certain novel features of construction, as will be more fully described and particularly pointed out in the appended claims.

In the accompanying drawings:

Figure 1 is a top plan view with the cover removed of a gear box for a testing machine embodying my invention;

Figure 2 is a vertical section taken substantially along line 2-2 of Figure 1;

Figure 3 is a similar view taken substantially along line 3-3 of Figure 1;

Figure 4 is asectional view of a fragmental portion of the gear box taken substantially along line 44 of Figure 1;

Figure 5 is a sectional view of a fragmental portion of the gear box and showing the yoke arrangement for operating a clutching device forming part of the invention;

Figure 6 is a sectional view taken substantially along line 66 of Figure 2 but omitting a plurality of elements so as to more clearly illustrate the drive shaft and elements physically related thereto;

Figure '7 is an edge view of the gear box with a portion of the testing machine associated therewith;

Figure 8 is an elevational view illustrating the relative position of certain elements of the gear box;

Figure 9 is a view of the clutching device and means for controlling the same; and

Figure 10 is an elevational View of certain elements shown in Figure 9.

The invention comprises providing a movable support for the tiltable beam of an inclined plane type testing machine. The support is in the form of a platform mounted at one end of a rack. The rack is reciprocated by means of a gear pinion. Motion is transmitted from a suitable power source, such as "an electric motor, by means of a plurality of gears which are automatically placed into or out of'motion transmitting relation. Manually operable means are also provided which the operator may actuate at will to automatically place certain of the gears in neutral relation upon a change in di- 3 rection of motion of the rack during the progress of a test. Manual means are also provided operable for changing the direction of movement of the said rack while in motion whereby the rack may be reversed in its movement during the progress of a test.

With reference to the drawings, (see Figure 7) designates a rack which is reciprocally mounted and shown in the present instance as adapted to be used with a testing machine of the inclined plane type wherein the force is applied to a specimen by means of a weighted carriage movable on a pivoted beam. The rack has attached thereto a support it on which rests the beam ii of the machine. The beam moves downwardly by gravity and is controlled in its movement by the rack. The rack i5 is reciprocated by a gearing mechanism designated generally [8 (see Figure l) which is contained within a casing it having a bottom, front, rear, and side Walls 26, El, 22, and 23 respectively. A clo sure 2c is removably secured to the casing, such as by being bolted in place by screws (not shown). The casing is sealed so as to hold lubricant to a depth therein sufficient to lubricate the moving elements of the gearing mechanism.

The casing is also provided with a well 25 (see Figures 1 and 6) the walls of which extend from the bottom 2%} upwardly to the plane of the upper edges of the casing.

well 25 is closed by means of walls 21 (see Figure 2), depending from the top wall of the closure in line with and engaging the upper edge of the walls of the well. An opening 28 extends through the bottom of the well and aligns with a similar opening 2%! in the closur 24. Guide bushings 3B and 3! similar to each other are received in these openings and are there secured in place, in any manner (not shown). The rack extends through these guide bushings and is guided thereby in the movement thereof.

The rack I5 is engaged by a pinion gear 32 .-(see Figure 1) positioned within the well and mounted on a shaft 33 which is journaled at one end in a bearing 34 formed in the front wall 2| of the casing and at the other end in a bearing opening 35 in the wall of the well. The rotation of the shaft 33 in a counterclockwise direction as viewed from the front of the machine,

will move the rack downwardly to impart a working stroke thereto. to control the movement of the beam H. The movement of the shaft in the other direction will impart a return movement to the rack to move the beam I? to initial posiv tion.

Motion i transmitted to the shaft 33 by means of a worm gear 36 secured to the shaft so as to rotate therewith (see Figures 1 and 2). This worm gear is engaged by a worm 3? that is fixed to a shaft 38 so as to rotate therewith. Shaft 38 extends at right angles to the shaft 33, and the ends thereof are journaled in the bearing openings 39 and ie provided in the side walls '23 of the casing. These openings are sealed by The upper portion of the on for free rotation on the shaft and has a hollow portion 50, the inner walls 5! of which taper inwardly providing a socket member 52 of a cone clutching device designated generally 53. The helical gear 59 is prevented from endwise movement by means of grooves 54 provided in the shaft on either side of the gear 49 and engaged by split rings 55. The other or male member 55 of the clutching device is slidably mounted on the shaft 38 and is provided with a tapered periphery 5? providing the frustro-conical surface which is frictionaly engageable with the surface 5!. The clutch cone 56 is also provided with a hub portion 58 having an annular groove 59 and a projection 60 which is received in the recess All in the worm gear @5, whereby the clutch cone 55 and worm gear 45 will be joined to each other for rotational movement as a unit.

The clutching device 53 is controlled by means of a yoke element St (see Figure 5) having opposite depending arms 62 and 63 between which is movably mounted a clutch thrust ring 64 such as by means of pins '65 extending through the arms as and 63 into the ring 64. The yoke 6| also has a projection 63 (see Figure 9) through which there extends a threaded member 61 for a purpose to be hereinafter described. The yoke is mounted on a shaft 88 which finds bearings in openings 69 and ill (see Figure 5) provided in the front and rear walls 2i and 22 of the casing. These openings are sealed by plates H and 12, which plates also serve to position shaft 88 and clutch thrust ring 64.

The clutch shaft 53 is rocked by means of a lever arrangement designated generally 73 (see Figures 3, 5, and 6). The arrangement comprises a lever "M which is secured at one end thereof to the shaft 68 such as by a pin fastenand depends therefrom generally vertically. A second lever 75 is pivotally mounted at one end thereof on the shaft 58 for relative movement therewith, and also has an arm TI depending therefrom and is provided with a shelf '53 extending laterally of the arm if on either side of the shaft '53 (see Figure 3) An arcuate or so-ca'lled horseshoe spring 59 has one horn thereof attached to the lever 7'6 as by means of a pin 83, and the other horn is attached to the lever H as by means of a similar pin 35. The spring tends to maintain these two levers apart; that is, the thrust exerted by the spring is such that the lower ends of these levers will be moved away from each other. A d lever 82 (see Figure 3) is also pivotally mounted on the shaft S8 and has an arm 83 extending gen rally horizontal and ears 84 and '65 ext: ding on either side of the shaft '58 and directly hove the shelf '13. Each car has a threaded abutment :36 and 3? adjustabl secured therein which extends therefrom into engagement with the shelf i8, whereby upon movement of the lever 32 motion therefrom will be transmitted to the lever it to move the same about the shaft The lever 82 is moved coLuiter-clockwise by ns of a control rod 88 having a collar 39 d thereto and against which the arm 8313f the r engages. A pull spring has one end atied to the lever as at 5i, and the other to an nor pin Upon a downward movement of e control rod 88, the lever 82 will be yieldin ly 16, will expand and swing the lever is in a counter-clockwise direction, as viewed in Figure 3, and rock the yoke to clutch the members 52 and 56 into frictional engagement whereby the clutch shaft 38 will now be in driving relation with the gear 49. Upon movement of the control rod 88 in the opposite direction the lever I5 will be moved past the lever '55 from the opposite direction and the spring 39 will move the lever It to rock the yoke shaft 58 to disengage the clutch device 53.

Motion is transmit ed to the clutch shaft by means of worms 93 and 9 5, which are selectively moved into engagement with the worm gear 43 or 55 (see Figures 4 and 6). These two worms 93 and 54 are left and right band respectively and are mounted on a rocker designated generally 55, which is rockably mounted so as to move either one or the other of the worms into engagement with the worm gears. The rocker 95 consists of plates 36 and Q! having central aligned openings 98 and 98 and joined by a cross member 99. A rod I30 extends between the plates 96 and 9? at one edge thereof and is secured in place such as by a pin fastening Iiii. This rod I39 is of a length to extend beyond the plate 3?. A similar .rod I92 extends between the plates at the opposite edge thereof and is secured in place such as by a pin fastening I113. The rod 32 is also of a length to extend beyond the plate sl. The worm 93 is mounted for rotation on the rod I33, which rod also carries a gear I52 which is joined to the worm 93 so as to rotate therewith by means of a coupling I35. The coupling 355 comprises a bushing mounted for free rotation on the rod I33 and is provided with a collar Est intermediate the ends thereof and has a portion I8? which is received in the gear I04 and there secured such as by means of a spline connection I98. The coupling is also provided with a reduced portion I89 which has a recess I It in the end thereof and receives therein a projection III extending from the adjacent side of the worm 33. Endwise movement of the worm 33 and the gear I54 on the rod IE5 is prevented by means of a collar IE2 positioned between the plate 9'! and the worm 93 and a collar i I3 positioned between the gear Hi4 and the plate I35. The worm 94 is similarly mounted on the rod I82 and attached to a gear H4 by means of a like coupling H5. Endwise movement also prevented by means of collars H5 and Ill. The rocker 95 is mounted for rockillg movement on a shaft I59, so as to place either of the worm 93 or 94 into engagement with the worm gears #35 and 43 respectively. The shaft which is the main drive shaft of the gear unit extends through openings 98 and 95' in the rocker and is, journaled in bearing openings are and I2I formed in the front and rear walls of the casing.

The gears I34 and H4 are rotated by means of a gear pinion I22, which is mounted on the shaft IIS so as to rotate therewith. The gear pinion I22 is positioned between the gears m4 and H4, whereby upon rotation of the shaft I III the gears I04 and I I4 will be rotated in the same direction. There is also mounted on the shaft H9 a gear pinion I23 which meshes with the gear 49 on the clutch shaft. These two gear pinions are connected to rotate with each other by means of a coup ing I24 positioned between the gear pinions, there being end splines I25 and I25 which engage in complementary recesses in the adjacent sides of the gear pinions I22 and I23. The coupling may be secured to the shaft such as by means of a pin fastening I21. Endwise movement of the rocker passes.

gear pinions and rocker on the shaft is prevented by a collar I29 positioned'between the gear. pinion I23 and the plate 91 and a collar I3l positioned between thegear pinion I22 and the plate 98.

The rocker is moved about the shaft H9 by means of a lever I32 (see Figures 3 and 8), having 1 a bifurcated arm I33 which extends into engagement with the end portion of the rod I02. The lever is pivotally mounted on a pivot pin 13. fastened to the wall 22 of the casing. Moving'the lever about the pivot I34 will move the rocker about the shaft in either one or the other direc:- tion. The lever I32 which will be now referred to as the kick-off lever is moved by means of the control rod 88. The control rod extends through the casing beyond the top and bottom thereof; and on this rod 33 there is provided a collarv I35 having a shoulder I35 facing the shoulder I31 provided on the collar 39, previously described (see Figure 3). The end of the lever I32 extends between and is in the path of movement of the shoulders I35 and I31 to be engaged thereby upon movement of the rod 83 a sufficient distance in either direction. The control rod is reciprocated by means of an abutment or trip dog I38 (see Figure 7), which is adjustably secured to the rack I5 above the casing in position to engage the upper end of the control rod 88. A thumb screw I39 is provided for readily adjusting the trip dog I38 along the length of the rack I5. A similar trip dog I4!) is also adjustably secured to the portion of the rack below the casing and is in position to engage the lower end of the control rod 88. Upon a predetermined downward distance of travel of the rack I5, the trip dog I38 will engage the upper portion of the rod 88 and move the same therewith. Upon the reversal of the travel of the rack I5, the trip dog I40 will engage the lower end of the control rod 88 and move the same in the opposite direction;

In order to provide a quick or snap action for swinging the rocker from one side or. the other, a trip lever MI is provided (see Figures 3, 6, and 8). The trip lever MI is a straight lever providing opposite arms I42 and I43 and is pivotally mounted on the drive shaft H9. The extreme portion of the arm I43 extends between the collars 83 and I35 in engagement therewith to be moved thereby upon movement of the control rod. The arm I43 is also provided with an arcuate slot I44 through which the rod I52 of the The longitudinal axis A (see Figure 8) of the trip lever MI is normally on one side or the other of a plane P passing centrally through the rod I5! and I32 and the shaft H9. A horseshoe spring I has one horn thereof attached to the arm I43 by means of a pin I46 and the other to the rod I62. A similar spring I41 has one horn thereof attached to the end portion of the arm I4! such as by means of a pin I43 and the other to the rod I38. When the. relative position between the rocker and the lever MI is as shown in Figure 8, the springs I45 and I I! will be at the maximum expansion, which is sufficient to oppose a free movement of the rocker about its pivot. When the lever I4I is moved by the movement of the control rod 88 in either direction a distance sulficient to move the axis A into register with the plane P, the horns of the springs will have been moved towards each other to contract or place the springs in maximum compression. See Figure 3 wherein the connecting points I43, I06, H32 and I45 are all in line at the instant the control rod 88 has been moved in either direction to compress the springs and I4! to their maximum compression. Upon further movement of the control rod 86, the kick-off lever I32 will have been engaged and moved sufiicient to swing the axis A of the rocker 95 past the plane P whereupon the springs will expand and force the connecting points Hi8 and H30 apart, and similarly 252 and 45 to corntinue the movement of the rocker by a snap action.

It is often desirable to reverse the movement of the rack I5 manually, and to this end a manually controlled lever hit is secured to a shaft I50 such as by means of a pin fastening I51 (see Figures 1, 2, and 3). The extreme end portion of the lever I49 extends to engage the upper side of the collar 89. The shaft I58 is journaled in the side wall 23 and the front walls 2i, and extends therebeyond and is provided with a handle I52. A pull spring 53 is attached to the shaft-such as by a link connection I56 to bias the lever I49 into engagement with the collar 85. It will be apparent that the rotation of the shaft 555 in a clockwise direction, as viewed in Figure 1, will move the lever I49 attached thereto so as to move the control rod 88 downwardly and thereby cause the rocker to be swung about the shaft I 19 so as to reverse the direction of movement of the rack I5 and cause it to ascend conversely; if the rack I5 is ascending, motion of shaft E55 counterclockwise will move control rod 88 upwardly, causing the rocker to reverse and cause the rack to descend.

Power may be applied to the gearing mechanism through any suitable source, preferably by means of an electric motor (not shown) and is transmitted therefrom through the motor shaft I55 connected to the main drive shaft IIS by means of a coupling I35 (see Figure 1). With the motor in motion, power is transmitted through the gear pinion I22 to the gear Wheels I04 and H4, and the worms 53 and 95 coupled therewith. Motion is also transmitted to the gear 49 through the gear pinion 23. Swinging the rocker about the shaft in a direction to place either of the worms 93 and 94 into engagement with the worm gears 43 and 45 will transmit motion to the clutch shaft and rotate the same in either one or the other direction at equal speeds. Clutching the gear 69 to place the same into driving engagement with the clutch shaft 38 will rotate this clutch shaft through the gear 49 at a greater speed than either of the gears 43, 45.

In order to block the clutching device from operating at such times as when either of gears 43 or 45 is engaged by worms 53 or 94 I mount a lever I51 for free rotation upon the shaft 68 (see Figures 2, 5, 9, and This lever depends generally vertically from the shaft and is provided with a recess I58 opening into the side I59 thereof and is provided with a shell E55 which is positioned to be engaged by the member 5'! heretofore mentioned and carried by the projection 66. The lever also has a pin ifil projecting therefrom. A pull spring lt2 is attached at one end to the lever and at the other end to a pin I83 whereby the lever is spring urged in one direction. A cam I5 3 is mounted on a shaft 565 to be rotated thereby. The shaft 155 is journaled in a bearing opening 155 in the front wall ZI of the casing and extends therefrom, and is provided with a knob i8? for manually rotating the cam I84. The cam is provided with abut- .ments I68 and I69 in the form of a curved surface to engage the shaft II 9 so as to limit the movement of the cam in either one .or the other direction. A pull spring III] is attached at one end to the cam as at Ill and the other end is suitably anchored to the stud I63 to bias either of the abutments I68, I59 into engagement with the shaft H9. When it is desired to keep the gear 49 out of driving relation with the shaft 38, the high point of the cam H2 is positioned so as to be engaged by the pin Ifii (see Figure 2) so as to maintain the lever at the position shown in Figure 2. With the lever in this position the shelf I65 will be so positioned as to engage the member 67 and prevent the rotation of yoke member BI and the engagement of member 55 with the socket 50.

When it is desired that the gear 49 be placed into driving relation with the shaft 38, the cam 165 is rotated counterclockwise to remove the high point I'i'2 thereof from engagement with the pin 56] (see Figure 10). The lever I5? will then be permitted to move by means of the pull spring E82, but will be arrested in this movement by the surface 15$ engaging the rod 555. Upon a subsequent rocking or swinging of the rocker, the rod I will at one point in its movement be in a position to enter the slot I58. The lever I57, under the urge of the spring H32, will move to receive the rod I511 in the slot and arrest further movement of the rocker and thus place the worms 93 and 94 in a neutral position. The shelf iSl'I on the lever I52 will then be in spaced relation with the member 5? whereby freeing shaft 68 to be controlled by the interaction of levers 82, T4, and F5 to clutch the gear '29 into driving relation with the clutch shaft 38.

The relative position of the components of the gear mechanism, at the start of the operating cycle, is such that the rack E5 is placed in the upper position. The motor is assumed to be in motion. The rocker $5 is locked in the neutral position by means of the rod I5$ engaging in the recess 158 in the neutral lever I557. The collars 8S and I35 are properly adjusted along the control rod 88 whereby to position the trip lever Edi past the rocker as with the springs I 45 and It! in compression to swing the rocker to place the worm as into engagement with the worm gear 53 upon release of the rocker 95 from the neutral position. To set the gearing mechanism in motion after the motor has been actuated, the cam IE5 is rotated clockwise and the high side I72 thereof will engage the pin itl to disengage and maintain the neutral lever I57 out of engagement with the rock-er 95 (see Figure 2), whereupon the rocker 95 under the influence of the springs M5 and id! will be swung about the shaft 5 I5 to place the worm 53 in engagement with the worm gear 45. Motion will now be transmitted through the worm gear 35 to rotate the clutch shaft 38 in a direction to move the rack I5 downwardly. Upon a predetermined distance of downward travel of the rack I5, the trip dog H38 attached thereto will engage the control rod 88 and move the same therewith to actuate the trip and kick-off levers MI and I42 respectively, whereby through the action of the springs I45 and 147 the rocker .95 will be swung in the opposite direction to disengage worm gear and worm 45, .93 and place worm gear and worm 43, 94 into engagement. Motion will now be transmitted through the worm gear 43 to rotate the clutch shaft at the same speed but in the opposite direction and move the rack I5 upwardly. Upon .a

predetermined upward distance of travel of the rack I5, the trip dog I49 thereon will engage the other end of the control rod 88 and move the same to actuate the trip and kick-off levers MI and I42 from the opposite direction and swing the rocker 95 to disengage the worm gear and worm 45, 93 and re-engage worm gear and worm 43, 94. This motion will continue uninterrupted while the cam I94 engages the pin IiII of the neutral lever I51.

In order to position the rocker 95 in a neutral position, the cam I64 is rotated counter-clockwise. to place the low side thereof opposite the pin I6I. The neutral lever will now be permitted to move by the spring I62 and the side- I59 thereof will come to rest on the rod I99. Upon a subsequent movement of the rocker, the rod I99 will ride into the recess I58 and be locked in neutral position, which will place both the worms 93 and 94 out of engagement with the worm gears 43 and 45. Should the cam I64 be rotated to place the rocker 95 in a neutral position, while the rack I is moving downwardly, the rocker 95 will be swung as previously described to disengage the worm gear and worm 43, 94 when the rack I5 has been moved the predetermined downward distance. The'movement of the neutral lever I51 under the influence of the spring I62 to engage the rod I99, will space the shelf I 59 from the member 91. shelf ISO in this position (see Figure 9) the clutching device 55 will be moved by the action of the levers I3, I5, and 82 to connect the clutch shaft 38 with the gear 49, in the manner previously described. Motion will now be transmitted to the shaft 38 through the gear 49 in a direction to move the rack upwardly to initial position at an accelerated speed and there come to rest. Should the cam I64 be rotated to place the rocker in a neutral position while the rack is moving upwardly by means of worm and worm gears 94 and 43, the rocker 95 will be swung at the upper limit of the rack, in a direction to disengage the worm gear and worm 43 and 94, and

since the clutch device 53 is out of engagement, s.

there will be no gearing engagement to drive shaft 38 and the rack I5 will come to rest in the upward initial position.

In Figure 2 the various elements of the gear unit are shown operable for providing a motion for conducting a hysteresis test. The rack I5 is shown moving upward at the instant before reversing. Upon further movement of the rack in the same direction, the trip dog I49 will engage and move the control rod 98 in the same direction to actuate and move the rocker to disengage the'worm gear and worm 43, 94 respectively and engage the worm gear and worm 45, 93 to reverse the direction of travel of the rack. This motion above stated will continue until the rack is brought to rest in a manner as previously described.

In operating the gearbox for a tensile test, cam IE4 is rotated to its limit clockwise, actuating rocker 95 and starting the operating cycle in the same manner as for the hysteresis test heretofore described. After rack I5 has 1 started downward, with worm engaging worm gear 93, cam I64 is rotated counter-clockwise to its limit, allowing neutral lever I51 to contact shaft end I99. Mechanisms are now positioned as shown in Figure- 10, as previously described,

whereby, when-rack I5 reaches the bottom of its stroke and is-reversed, rocker 95 rotates to neutral, engaging shaft end I99 in slot I58, both sets With the of worms and worm gears 93' and-45, and 94- and 43 are disengaged, clutching mechanism 53 is engaged, drawing rack upward at high speed, where it stops at the top of its stroke.

In some forms of hysteresis testing it is desirable to apply a reversin stress to the sample while it is under a partial load. This may be accomplished, provided first that rack I5 isallowed to travel downward from starting position approximately one-fifth of its total travel, by-rotating operating handle I52 clockwise and counter-clockwise, thus reversing and rereversing the direction of the rack and hence the machine load. Handle I52 may be swung from side to side in this manner as many times as desired and, within reasonable limits as rapidly as desired, giving to rack I5 a very short up and-down motion. This special operation may be per-.- formed from either upward or downward motion of the rack. It is also sometimes desirable, either because 7 of the test sample breaking prematurely or for some other reason, to return the testing instrutil) ment to its starting position without. waiting for the full cycle to be completed. For this-pur+ pose the operator may at will, rotate thecontrol knob IBI counter-clockwise thus setting neutral lever into the aspect shown in Figure 10, then move operating handle I52 clockwise if the rack is travellin downward or counter-clockwise if the rack is rising. Such motion of the control handle I52 will disengage the rocker and enclutch the high speed gearing, ina manner previously described, causing the rack to travel upward at high speed to -stop at the top 'ofi'ts stroke. While I have shown and described a gear unit associated with a testing machine of the inclined plane type, the gear unit is also adapted tob used in testing machines wherein 'a force is a'p plied directly to the specimen throughthe'rack or a similar element.

I claim: 7 I

1. In a testing machine, a rack mounted for reciprocal movement for controlling the applica-' tion of force to a specimen, agear unit operable for reciprocating said rack comprising a shaft mounted for rotation in either direction and 0p; eratively connected to said rack for reciprocating the same, a first means including a right hand gear fixed to said shaft for rotating said shaft in onedirection, a second means including a lefthand gear fixed to said shaft for rotating said shaft in the other direction, a third means for rotating said shaft in the said other direction at an accelerated speed, said third means including a gear mounted for free movement on said shaft, a clutching device fOr connecting said gear to said shaft for rotating the same, and means for selecting either the said second or third means for rotating said shaft. j I

2. In a testing machine, arack mounted for reciprocal movement for controlling the application of force to a specimen, a gear unit operable for reciprocating said rack comprising a shaft mounted for rotation-in either directionand .opf eratively connected to said rack for reciprocating the same, a first means including a rightQhand gear fixed to said shaft for rotating said shaft in one direction, a second means includin alefte hand gear fixed to said shaft for rotating said shaft in the other direction, a third meansfonro tatin said shaft in the said other direction at accelerated speed, and means for selecting either the said second or third means for rotating said shaft, the last said means being operable during progress of a test.

3. In a testing machine, a member mounted for reciprocal movement for controlling the application of force to a specimen, a train of gears for moving said member in one direction including a right-hand gear fixed to said shaft, a second train of gears including certain gears of the first said train of gears and a left-hand ear fixed to said shaft for moving said member in the other direction at a speed equal to the movement of said member in the first said direction, a third train of gears includin certain gear in the said first and second train of gears for moving said member in the said other direction at an increased speed, and means for selecting either of said second or third train of gears for moving said member in the said other direction.

4. In a testing machine, a rack mounted for reciprocal movement, a gear unit for reciprocating said rack, means to operate said unit to reciprocate said rack at the same speed in either direction and also operate said rack at one speein one direction and at an increased speed in the other direction, said ear unit comprising a shaft operatively connected to said rack, gear means including a right-hand gear fixed to said shaft for rotatin the same in one direction, a second gear means including a left-hand gear fixed to the shaft for rotating said shaft in the other direction at the same speed, a third gear means for rotating said shaft in one direction at an increased speed and means operable for selecting either of second or third gear means for rotating said shaft.

5. In a testing machine, a rack mounted for reciprocal movement, a gear unit for reciprocating said rack, means to operate said unit to reciprocate said rack at the same speed in either direction and also operate said rack at one speed in one direction and at an increased speed in the other direction, said gear unit comprising a shaft operatively connected to said rack, gear means including a right-hand gear fixed to said shaft for rotatin said shaft in one direction, a second gear means including a left-hand gear fixed to said shaft for rotatin said shaft in the other direction at the same speed, a third gear means carried by said shaft for rotating the same in the said other direction at an increased speed, and aclutching device for operatively connecting said third gear means to said shaft.

6. In a gear box for a testing. machine a reciprocally mounted rack, a rotatably mounted shaft operatively connected to said rack through which motion is transmitted androtatable in one direction for imparting a working stroke to said rack and. rotatable in the other direction for imparting a. return movement to said rack, a rightand left-hand worm gear 011 said shaft, a right-hand worm mounted to be movable in and out of engagement with said right-hand worm gear, a lefthand; worm mounted to be movable in and out of engagement with said left-hand worm gear, means for moving said worms alternately i and out of engagement with said Worm gears and means for rotating said worms.

7. In a gear box as set forth in claim 6 wherein said means comprises a rocker on which said worms are mounted.

8. In a gear box for a testing machine, a reciproca-lly mounted rack, a rotatable shaft operatively-= connected to said rack through which mo tion is transmitted to said rack for imparting a working stroke thereto in one direction and a return movement in the other direction, a rightand left-hand worm gear of equal size on said shaft for rotating the same in one or the other direction at the same speed, a gear rotatably mounted on said shaft, a clutching device for connecting said gear to said shaft for rotating the same, said gear being of a size to rotate said shaft at a greater speed than said worm gears, a right-hand Worm mounted to be moved in and out of engagement With said right-hand worm 'gear, a left-hand Worm mounted to be moved into and out of engagement with said left-hand worm gear, and means for blocking the operation of said clutch when either of said worms are moved into engagement with said worm gears.

9. In a gear box as set forth in claim 8 wherein means are provided for blocking the movement of said rightand left-hand worms into engagement with said right and left worm gears when said gear is connected. to said shaft to rotate the same.

10. In a testing machine, a rack mounted for reciprocal movement for controlling the application of force to a specimen, a gear unit operable for reciprocating said rack comprising a shaft mounted for rotatio in either direction and operatively connected to said rack for reciprocating the same, a first means including a right-hand gear fixed to said shaft for rotating said shaft in one direction, a second means including a lefthand: gear fixed to said shaft for. rotating said shaft in the other direction, a third means for rotating said shaft in the said other direction at an eccelerated speed, said third means including a gear mounted for free movement on said shaft, a clutching device for connecting said gear to said shaft for rotating the same, means for selecting either the said second or third means for rotating said shaft, and means for blocking the operation of said clutch when either of said first and second means are selected for rotating said shaft.

11. In a gear box for a testing machine, a reciprocally mounted rack, a rotatably mounted shaft operatively connected to said rack through which motion is transmitted, gear means for rotating said shaft, said gear means including a gear rotatably mounted on said shaft, a rocker shaft, a clutching device operatively connected to said shaft and operated thereby upon the rocking'of said rocker shaft for connecting said gear to said rotatable shaft for rotating the same, re-

. siliently yielding means for rocking said rocker shaft, and an arm movably mounted on said rocker shaft and movable into position to be engaged by said clutching device to block the movement thereof.

12. In a gear box as set forth in claim 11 wherein said arm is spring loaded to be moved in the opposite direction, and cam means for moving said arm in the clutch engaging position.

LOUIS BLUMENBAUM.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,552,516 Sternkopf Sept. 8, 1925 1,911,507 Demkier et a1. July 11, 1933 2,055,523 Dingeldein Sept. 29-, 1936 

